One obvious method of increasing LCO yield is to reduce the FCC unit cracking severity so that conversion declines. At the lower conversion, yields of heavy products (light cycle oil, heavy cycle oil, and clarified oil) will increase while yields of light products (gasoline, LPG, and gas) and coke will decrease. The cracking severity can be reduced in several ways reducing catalyst activity, lowering reactor temperature, and reducing the catalystoil ratio are three common ways. These three alternatives have some similarities and differences, which are illustrated in Figure 1.